The Molluscan Fauna of the Florida Middle Grounds with Comments on its Zoogeographical Affinities

Abstract

Recent studies have indicated that the Gulf of Mexico is bom1ded by a discontinual series of hard substrates which support faunal and floral assemblages of both temperate and tropical Ol'igins. This substrate distTibution has had a significant impact on molluscan fauna in the Gulf of Mexico. An investigation of the molluscan fauna of the Florida Middle Grounds has produced 7 5 species associated with this high relief substrate which is also chamcterized by herma-typic COl'als, Although the molluscan fauna is comprised of forms which are predominantly "Caribbean eurythermic" and "Caribbean Restricted" (76%) which is similar in composition to the West Flower Garden Bank of Texas, their species composition is quite dissimilar (only 23% similaTity). For these and other reasons, it is proposed that the zoogeographic status of the Gulf of Mexico should be seriously l'econsidered by specialists in other faunal groups.